Linear compressor

ABSTRACT

A linear compressor is provided. The linear compressor includes a piston. The piston includes a piston cylinder having a head plate. The head plate defines a passage that extends through the head plate. A reed valve is mounted to the head plate and positioned over the passage of the head plate. A valve seat is positioned at and extends about the passage of the head plate.

FIELD OF THE INVENTION

The present subject matter relates generally to linear compressors, e.g., for refrigerator appliances.

BACKGROUND OF THE INVENTION

Certain refrigerator appliances include sealed systems for cooling chilled chambers of the refrigerator appliance. The sealed systems generally include a compressor that generates compressed refrigerant during operation of the sealed system. The compressed refrigerant flows to an evaporator where heat exchange between the chilled chambers and the refrigerant cools the chilled chambers and food items located therein.

Recently, certain refrigerator appliances have included linear compressors for compressing refrigerant. Linear compressors generally include a piston and a driving coil. The driving coil receives a current that generates a force for sliding the piston forward and backward within a chamber. During motion of the piston within the chamber, the piston compresses refrigerant. However, friction between the piston and a wall of the chamber can negatively affect operation of the linear compressors if the piston is not suitably aligned within the chamber. In particular, friction losses due to rubbing of the piston against the wall of the chamber can negatively affect an efficiency of an associated refrigerator appliance.

The driving coil generally engages a magnet on a mover assembly of the linear compressor in order to reciprocate the piston within the chamber. The magnet is spaced apart from the driving coil by an air gap. In certain linear compressors, an additional air gap is provided at an opposite side of the magnet, e.g., between the magnet and an inner back iron of the linear compressor. However, multiple air gaps can negatively affect operation of the linear compressor by interrupting transmission of a magnetic field from the driving coil. In addition, maintaining a uniform air gap between the magnet and the driving coil and/or inner back iron can be difficult.

Accordingly, a linear compressor with features for limiting friction between a piston and a wall of a cylinder during operation of the linear compressor would be useful. In addition, a linear compressor with features for maintaining uniformity of an air gap between a magnet and a driving coil of the linear compressor would be useful. In particular, a linear compressor having only a single air gap would be useful.

BRIEF DESCRIPTION OF THE INVENTION

The present subject matter provides a linear compressor. The linear compressor includes a piston. The piston includes a piston cylinder having a head plate. The head plate defines a passage that extends through the head plate. A reed valve is mounted to the head plate and positioned over the passage of the head plate. A valve seat is positioned at and extends about the passage of the head plate. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In a first exemplary embodiment, a linear compressor is provided. The linear compressor includes a driving coil. An inner back iron assembly is positioned in the driving coil. The inner back iron assembly has an outer surface. A magnet is mounted to the inner back iron assembly at the outer surface of the inner back iron assembly such that the magnet faces the driving coil. A cylinder assembly defines a chamber. A piston is slidably received within the chamber of the cylinder assembly. The piston includes a cylindrical segment that extends between a first end portion and a second end portion. A head plate is mounted to the cylindrical segment at the second end portion of the cylindrical segment. The head plate defines a passage that extends from the second end portion of the cylindrical segment towards the first end portion of the cylindrical segment through the head plate. A reed valve is mounted to the head plate and positioned over the passage of the head plate. A valve seat is positioned at and extends about the passage of the head plate. The valve seat also extends away from the head plate such that the reed valve is positioned on the valve seat above the passage of the head plate when the reed valve is in a closed position. A coupling extends between the inner back iron assembly and the piston.

In a second exemplary embodiment, a linear compressor is provided. The linear compressor defines a radial direction, a circumferential direction and an axial direction. The linear compressor includes a cylinder assembly that defines a chamber. A piston is received within the chamber of the cylinder assembly such that the piston is slidable along a first axis within the chamber of the cylinder assembly. The piston includes a piston cylinder having a head plate. The head plate is positioned at an end of the piston cylinder. The head plate defines a passage that extends along the axial direction through the head plate. A reed valve is mounted to the head plate and positioned over the passage of the head plate. A valve seat is positioned at and extends about the passage of the head plate along the circumferential and radial directions. The valve seat also extends away from the head plate along the axial direction. A driving coil is operable to move the piston assembly along a second axis. The first and second axes being substantially parallel to the axial direction.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 is a front elevation view of a refrigerator appliance according to an exemplary embodiment of the present subject matter.

FIG. 2 is schematic view of certain components of the exemplary refrigerator appliance of FIG. 1.

FIG. 3 provides a perspective view of a linear compressor according to an exemplary embodiment of the present subject matter.

FIG. 4 provides a side section view of the exemplary linear compressor of FIG. 3.

FIG. 5 provides an exploded view of the exemplary linear compressor of FIG. 4.

FIG. 6 provides a side section view of certain components of the exemplary linear compressor of FIG. 3.

FIG. 7 provides a perspective view of a piston flex mount of the exemplary linear compressor of FIG. 3.

FIG. 8 provides a perspective view of a coupling according to an exemplary embodiment of the present subject matter.

FIG. 9 provides a perspective view of a machined spring of the exemplary linear compressor of FIG. 3.

FIG. 10 provides a perspective view of a piston of the exemplary linear compressor of FIG. 3.

FIG. 11 provides an exploded view of the piston of FIG. 10.

FIG. 12 provides a rear perspective view of the piston of FIG. 10.

FIG. 13 provides a top, plan view of certain components of the piston of FIG. 10.

FIG. 14 provides an exploded view of a piston according to another exemplary embodiment of the present subject matter.

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 depicts a refrigerator appliance 10 that incorporates a sealed refrigeration system 60 (FIG. 2). It should be appreciated that the term “refrigerator appliance” is used in a generic sense herein to encompass any manner of refrigeration appliance, such as a freezer, refrigerator/freezer combination, and any style or model of conventional refrigerator. In addition, it should be understood that the present subject matter is not limited to use in appliances. Thus, the present subject matter may be used for any other suitable purpose, such as vapor compression within air conditioning units or air compression within air compressors.

In the illustrated exemplary embodiment shown in FIG. 1, the refrigerator appliance 10 is depicted as an upright refrigerator having a cabinet or casing 12 that defines a number of internal chilled storage compartments. In particular, refrigerator appliance 10 includes upper fresh-food compartments 14 having doors 16 and lower freezer compartment 18 having upper drawer 20 and lower drawer 22. The drawers 20 and 22 are “pull-out” drawers in that they can be manually moved into and out of the freezer compartment 18 on suitable slide mechanisms.

FIG. 2 is a schematic view of certain components of refrigerator appliance 10, including a sealed refrigeration system 60 of refrigerator appliance 10. A machinery compartment 62 contains components for executing a known vapor compression cycle for cooling air. The components include a compressor 64, a condenser 66, an expansion device 68, and an evaporator 70 connected in series and charged with a refrigerant. As will be understood by those skilled in the art, refrigeration system 60 may include additional components, e.g., at least one additional evaporator, compressor, expansion device, and/or condenser. As an example, refrigeration system 60 may include two evaporators.

Within refrigeration system 60, refrigerant flows into compressor 64, which operates to increase the pressure of the refrigerant. This compression of the refrigerant raises its temperature, which is lowered by passing the refrigerant through condenser 66. Within condenser 66, heat exchange with ambient air takes place so as to cool the refrigerant. A fan 72 is used to pull air across condenser 66, as illustrated by arrows A_(C), so as to provide forced convection for a more rapid and efficient heat exchange between the refrigerant within condenser 66 and the ambient air. Thus, as will be understood by those skilled in the art, increasing air flow across condenser 66 can, e.g., increase the efficiency of condenser 66 by improving cooling of the refrigerant contained therein.

An expansion device (e.g., a valve, capillary tube, or other restriction device) 68 receives refrigerant from condenser 66. From expansion device 68, the refrigerant enters evaporator 70. Upon exiting expansion device 68 and entering evaporator 70, the refrigerant drops in pressure. Due to the pressure drop and/or phase change of the refrigerant, evaporator 70 is cool relative to compartments 14 and 18 of refrigerator appliance 10. As such, cooled air is produced and refrigerates compartments 14 and 18 of refrigerator appliance 10. Thus, evaporator 70 is a type of heat exchanger which transfers heat from air passing over evaporator 70 to refrigerant flowing through evaporator 70.

Collectively, the vapor compression cycle components in a refrigeration circuit, associated fans, and associated compartments are sometimes referred to as a sealed refrigeration system operable to force cold air through compartments 14, 18 (FIG. 1). The refrigeration system 60 depicted in FIG. 2 is provided by way of example only. Thus, it is within the scope of the present subject matter for other configurations of the refrigeration system to be used as well.

FIG. 3 provides a perspective view of a linear compressor 100 according to an exemplary embodiment of the present subject matter. FIG. 4 provides a side section view of linear compressor 100. FIG. 5 provides an exploded side section view of linear compressor 100. As discussed in greater detail below, linear compressor 100 is operable to increase a pressure of fluid within a chamber 112 of linear compressor 100. Linear compressor 100 may be used to compress any suitable fluid, such as refrigerant or air. In particular, linear compressor 100 may be used in a refrigerator appliance, such as refrigerator appliance 10 (FIG. 1) in which linear compressor 100 may be used as compressor 64 (FIG. 2). As may be seen in FIG. 3, linear compressor 100 defines an axial direction A, a radial direction R and a circumferential direction C. Linear compressor 100 may be enclosed within a hermetic or air-tight shell (not shown). The hermetic shell can, e.g., hinder or prevent refrigerant from leaking or escaping from refrigeration system 60.

Turning now to FIG. 4, linear compressor 100 includes a casing 110 that extends between a first end portion 102 and a second end portion 104, e.g., along the axial direction A. Casing 110 includes various static or non-moving structural components of linear compressor 100. In particular, casing 110 includes a cylinder assembly 111 that defines a chamber 112. Cylinder assembly 111 is positioned at or adjacent second end portion 104 of casing 110. Chamber 112 extends longitudinally along the axial direction A. Casing 110 also includes a motor mount mid-section 113 and an end cap 115 positioned opposite each other about a motor. A stator, e.g., including an outer back iron 150 and a driving coil 152, of the motor is mounted or secured to casing 110, e.g., such that the stator is sandwiched between motor mount mid-section 113 and end cap 115 of casing 110. Linear compressor 100 also includes valves (such as a discharge valve assembly 117 at an end of chamber 112) that permit refrigerant to enter and exit chamber 112 during operation of linear compressor 100.

A piston assembly 114 with a piston head 116 is slidably received within chamber 112 of cylinder assembly 111. In particular, piston assembly 114 is slidable along a first axis A1 within chamber 112. The first axis A1 may be substantially parallel to the axial direction A. During sliding of piston head 116 within chamber 112, piston head 116 compresses refrigerant within chamber 112. As an example, from a top dead center position, piston head 116 can slide within chamber 112 towards a bottom dead center position along the axial direction A, i.e., an expansion stroke of piston head 116. When piston head 116 reaches the bottom dead center position, piston head 116 changes directions and slides in chamber 112 back towards the top dead center position, i.e., a compression stroke of piston head 116. It should be understood that linear compressor 100 may include an additional piston head and/or additional chamber at an opposite end of linear compressor 100. Thus, linear compressor 100 may have multiple piston heads in alternative exemplary embodiments.

Linear compressor 100 also includes an inner back iron assembly 130. Inner back iron assembly 130 is positioned in the stator of the motor. In particular, outer back iron 150 and/or driving coil 152 may extend about inner back iron assembly 130, e.g., along the circumferential direction C. Inner back iron assembly 130 extends between a first end portion 132 and a second end portion 134, e.g., along the axial direction A.

Inner back iron assembly 130 also has an outer surface 137. At least one driving magnet 140 is mounted to inner back iron assembly 130, e.g., at outer surface 137 of inner back iron assembly 130. Driving magnet 140 may face and/or be exposed to driving coil 152. In particular, driving magnet 140 may be spaced apart from driving coil 152, e.g., along the radial direction R by an air gap AG. Thus, the air gap AG may be defined between opposing surfaces of driving magnet 140 and driving coil 152. Driving magnet 140 may also be mounted or fixed to inner back iron assembly 130 such that an outer surface 142 of driving magnet 140 is substantially flush with outer surface 137 of inner back iron assembly 130. Thus, driving magnet 140 may be inset within inner back iron assembly 130. In such a manner, the magnetic field from driving coil 152 may have to pass through only a single air gap (e.g., air gap AG) between outer back iron 150 and inner back iron assembly 130 during operation of linear compressor 100, and linear compressor 100 may be more efficient than linear compressors with air gaps on both sides of a driving magnet.

As may be seen in FIG. 4, driving coil 152 extends about inner back iron assembly 130, e.g., along the circumferential direction C. Driving coil 152 is operable to move the inner back iron assembly 130 along a second axis A2 during operation of driving coil 152. The second axis may be substantially parallel to the axial direction A and/or the first axis A1. As an example, driving coil 152 may receive a current from a current source (not shown) in order to generate a magnetic field that engages driving magnet 140 and urges piston assembly 114 to move along the axial direction A in order to compress refrigerant within chamber 112 as described above and will be understood by those skilled in the art. In particular, the magnetic field of driving coil 152 may engage driving magnet 140 in order to move inner back iron assembly 130 along the second axis A2 and piston head 116 along the first axis A1 during operation of driving coil 152. Thus, driving coil 152 may slide piston assembly 114 between the top dead center position and the bottom dead center position, e.g., by moving inner back iron assembly 130 along the second axis A2, during operation of driving coil 152.

Linear compressor 100 may include various components for permitting and/or regulating operation of linear compressor 100. In particular, linear compressor 100 includes a controller (not shown) that is configured for regulating operation of linear compressor 100. The controller is in, e.g., operative, communication with the motor, e.g., driving coil 152 of the motor. Thus, the controller may selectively activate driving coil 152, e.g., by supplying current to driving coil 152, in order to compress refrigerant with piston assembly 114 as described above.

The controller includes memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of linear compressor 100. The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory can be a separate component from the processor or can be included onboard within the processor. Alternatively, the controller may be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

Linear compressor 100 also includes a machined spring 120. Machined spring 120 is positioned in inner back iron assembly 130. In particular, inner back iron assembly 130 may extend about machined spring 120, e.g., along the circumferential direction C. Machined spring 120 also extends between first and second end portions 102 and 104 of casing 110, e.g., along the axial direction A. Machined spring 120 assists with coupling inner back iron assembly 130 to casing 110, e.g., cylinder assembly 111 of casing 110. In particular, inner back iron assembly 130 is fixed to machined spring 120 at a middle portion 119 of machined spring 120 as discussed in greater detail below.

During operation of driving coil 152, machined spring 120 supports inner back iron assembly 130. In particular, inner back iron assembly 130 is suspended by machined spring 120 within the stator of the motor such that motion of inner back iron assembly 130 along the radial direction R is hindered or limited while motion along the second axis A2 is relatively unimpeded. Thus, machined spring 120 may be substantially stiffer along the radial direction R than along the axial direction A. In such a manner, machined spring 120 can assist with maintaining a uniformity of the air gap AG between driving magnet 140 and driving coil 152, e.g., along the radial direction R, during operation of the motor and movement of inner back iron assembly 130 on the second axis A2. Machined spring 120 can also assist with hindering side pull forces of the motor from transmitting to piston assembly 114 and being reacted in cylinder assembly 111 as a friction loss.

FIG. 6 provides a side section view of certain components of linear compressor 100. FIG. 9 provides a perspective view of machined spring 120. As may be seen in FIG. 9, machined spring 120 includes a first cylindrical portion 121, a second cylindrical portion 122, a first helical portion 123, a third cylindrical portion 125 and a second helical portion 126. First helical portion 123 of machined spring 120 extends between and couples first and second cylindrical portions 121 and 122 of machined spring 120, e.g., along the axial direction A. Similarly, second helical portion 126 of machined spring 120 extends between and couples second and third cylindrical portions 122 and 125 of machined spring 120, e.g., along the axial direction A.

Turning back to FIG. 4, first cylindrical portion 121 is mounted or fixed to casing 110 at first end portion 102 of casing 110. Thus, first cylindrical portion 121 is positioned at or adjacent first end portion 102 of casing 110. Third cylindrical portion 125 is mounted or fixed to casing 110 at second end portion 104 of casing 110, e.g., to cylinder assembly 111 of casing 110. Thus, third cylindrical portion 125 is positioned at or adjacent second end portion 104 of casing 110. Second cylindrical portion 122 is positioned at middle portion 119 of machined spring 120. In particular, second cylindrical portion 122 is positioned within and fixed to inner back iron assembly 130. Second cylindrical portion 122 may also be positioned equidistant from first and third cylindrical portions 121 and 125, e.g., along the axial direction A.

First cylindrical portion 121 of machined spring 120 is mounted to casing 110 with fasteners (not shown) that extend though end cap 115 of casing 110 into first cylindrical portion 121. In alternative exemplary embodiments, first cylindrical portion 121 of machined spring 120 may be threaded, welded, glued, fastened, or connected via any other suitable mechanism or method to casing 110. Third cylindrical portion 125 of machined spring 120 is mounted to cylinder assembly 111 at second end portion 104 of casing 110 via a screw thread of third cylindrical portion 125 threaded into cylinder assembly 111. In alternative exemplary embodiments, third cylindrical portion 125 of machined spring 120 may be welded, glued, fastened, or connected via any other suitable mechanism or method, such as an interference fit, to casing 110.

As may be seen in FIG. 9, first helical portion 123 extends, e.g., along the axial direction A, between first and second cylindrical portions 121 and 122 and couples first and second cylindrical portions 121 and 122 together. Similarly, second helical portion 126 extends, e.g., along the axial direction A, between second and third cylindrical portions 122 and 125 and couples second and third cylindrical portions 122 and 125 together. Thus, second cylindrical portion 122 is suspended or sprung between first and third cylindrical portions 121 and 125 with first and second helical portions 123 and 126.

First and second helical portions 123 and 126 and first, second and third cylindrical portions 121, 122 and 125 of machined spring 120 may be continuous with one another and/or integrally mounted to one another. As an example, machined spring 120 may be formed from a single, continuous piece of metal, such as steel, or other elastic material. In addition, first, second and third cylindrical portions 121, 122 and 125 and first and second helical portions 123 and 126 of machined spring 120 may be positioned coaxially relative to one another, e.g., on the second axis A2.

First helical portion 123 includes a first pair of helices 124. Thus, first helical portion 123 may be a double start helical spring. Helical coils of first helices 124 are separate or spaced apart from each other. Each helical coil of first helices 124 also extends between first and second cylindrical portions 121 and 122 of machined spring 120. Thus, first helices 124 couple first and second cylindrical portions 121 and 122 of machined spring 120 together. In particular, first helical portion 123 may be formed into a double-helix structure in which each helical coil of first helices 124 is wound in the same direction and connect first and second cylindrical portions 121 and 122 of machined spring 120.

Second helical portion 126 includes a second pair of helices 127. Thus, second helical portion 126 may be a double start helical spring. Helical coils of second helices 127 are separate or spaced apart from each other. Each helical coil of second helices 127 also extends between second and third cylindrical portions 122 and 125 of machined spring 120. Thus, second helices 127 couple second and third cylindrical portions 122 and 125 of machined spring 120 together. In particular, second helical portion 126 may be formed into a double-helix structure in which each helical coil of second helices 127 is wound in the same direction and connect second and third cylindrical portions 122 and 125 of machined spring 120.

By providing first and second helices 124 and 127 rather than a single helix, a force applied by machined spring 120 may be more even and/or inner back iron assembly 130 may rotate less during motion of inner back iron assembly 130 along the second axis A2. In addition, first and second helices 124 and 127 may be counter or oppositely wound. Such opposite winding may assist with further balancing the force applied by machined spring 120 and/or inner back iron assembly 130 may rotate less during motion of inner back iron assembly 130 along the second axis A2. In alternative exemplary embodiments, first and second helices 124 and 127 may include more than two helices. For example, first and second helices 124 and 127 may each include three helices, four helices, five helices or more.

By providing machined spring 120 rather than a coiled wire spring, performance of linear compressor 100 can be improved. For example, machined spring 120 may be more reliable than comparable coiled wire springs. In addition, the stiffness of machined spring 120 along the radial direction R may be greater than that of comparable coiled wire springs. Further, comparable coiled wire springs include an inherent unbalanced moment. Machined spring 120 may be formed to eliminate or substantially reduce any inherent unbalanced moments. As another example, adjacent coils of a comparable coiled wire spring contact each other at an end of the coiled wire spring, and such contact may dampen motion of the coiled wire spring thereby negatively affecting a performance of an associated linear compressor. In contrast, by being formed of a single continuous material and having no contact between adjacent coils, machined spring 120 may have less dampening than comparable coiled wire springs.

As may be seen in FIG. 6, inner back iron assembly 130 includes an outer cylinder 136 and a sleeve 139. Outer cylinder 136 defines outer surface 137 of inner back iron assembly 130 and also has an inner surface 138 positioned opposite outer surface 137 of outer cylinder 136. Sleeve 139 is positioned on or at inner surface 138 of outer cylinder 136. A first interference fit between outer cylinder 136 and sleeve 139 may couple or secure outer cylinder 136 and sleeve 139 together. In alternative exemplary embodiments, sleeve 139 may be welded, glued, fastened, or connected via any other suitable mechanism or method to outer cylinder 136.

Sleeve 139 extends about machined spring 120, e.g., along the circumferential direction C. In addition, middle portion 119 of machined spring 120 (e.g., third cylindrical portion 125) is mounted or fixed to inner back iron assembly 130 with sleeve 139. As may be seen in FIG. 6, sleeve 139 extends between inner surface 138 of outer cylinder 136 and middle portion 119 of machined spring 120, e.g., along the radial direction R. In particular, sleeve 139 extends between inner surface 138 of outer cylinder 136 and second cylindrical portion 122 of machined spring 120, e.g., along the radial direction R. A second interference fit between sleeve 139 and middle portion 119 of machined spring 120 may couple or secure sleeve 139 and middle portion 119 of machined spring 120 together. In alternative exemplary embodiments, sleeve 139 may be welded, glued, fastened, or connected via any other suitable mechanism or method to middle portion 119 of machined spring 120 (e.g., second cylindrical portion 122 of machined spring 120).

Outer cylinder 136 may be constructed of or with any suitable material. For example, outer cylinder 136 may be constructed of or with a plurality of (e.g., ferromagnetic) laminations 131. Laminations 131 are distributed along the circumferential direction C in order to form outer cylinder 136. Laminations 131 are mounted to one another or secured together, e.g., with rings 135 at first and second end portions 132 and 134 of inner back iron assembly 130. Outer cylinder 136, e.g., laminations 131, define a recess 144 that extends inwardly from outer surface 137 of outer cylinder 136, e.g., along the radial direction R. Driving magnet 140 is positioned in recess 144, e.g., such that driving magnet 140 is inset within outer cylinder 136.

A piston flex mount 160 is mounted to and extends through inner back iron assembly 130. In particular, piston flex mount 160 is mounted to inner back iron assembly 130 via sleeve 139 and machined spring 120. Thus, piston flex mount 160 may be coupled (e.g., threaded) to machined spring 120 at second cylindrical portion 122 of machined spring 120 in order to mount or fix piston flex mount 160 to inner back iron assembly 130. A flexible or compliant coupling 170 extends between piston flex mount 160 and piston assembly 114, e.g., along the axial direction A. Thus, compliant coupling 170 connects inner back iron assembly 130 and piston assembly 114 such that motion of inner back iron assembly 130, e.g., along the axial direction A or the second axis A2, is transferred to piston assembly 114 as discussed in greater detail below.

FIG. 7 provides a perspective view of piston flex mount 160. As may be seen in FIG. 7, piston flex mount 160 defines at least one passage 162. Passage 162 of piston flex mount 160 extends, e.g., along the axial direction A, through piston flex mount 160. Thus, a flow of fluid, such as air or refrigerant, may pass though piston flex mount 160 via passage 162 of piston flex mount 160 during operation of linear compressor 100.

FIG. 8 provides a perspective view of compliant coupling 170. As discussed above, compliant coupling 170 extends between inner back iron assembly 130 and piston assembly 114, e.g., along the axial direction A, and connects inner back iron assembly 130 and piston assembly 114. In particular, compliant coupling 170 transfers motion of inner back iron assembly 130 along the axial direction A to piston assembly 114. However, compliant coupling 170 is compliant or flexible along the radial direction R. In particular, compliant coupling 170 may be sufficiently compliant along the radial direction R such little or no motion of inner back iron assembly 130 along the radial direction R is transferred to piston assembly 114 by compliant coupling 170. In such a manner, side pull forces of the motor are decoupled from piston assembly 114 and/or cylinder assembly 111 and friction between piston assembly 114 and cylinder assembly 111 may be reduced.

Compliant coupling 170 extends between a first end portion 172 and a second end portion 174, e.g., along the axial direction A. First end portion 172 of compliant coupling 170 may be mounted (e.g., threaded) to inner back iron assembly 130, e.g., at first end portion 132 of inner back iron assembly 130. Second end portion 174 of compliant coupling 170 may be mounted (e.g., threaded) to piston head 116.

FIG. 10 provides a perspective view of piston assembly 114. FIG. 11 provides an exploded view of piston assembly 114. As may be seen in FIG. 11, piston assembly 114 defines at least one conduit or passage 118. Passage 118 of piston assembly 114 extends, e.g., along the axial direction A, through piston assembly 114. Thus, the flow of fluid may pass though piston assembly 114 via passage 118 of piston assembly 114 into chamber 112 during operation of linear compressor 100. In such a manner, the flow of fluid (that is compressed by piston assembly 114 within chamber 112) may flow through piston flex mount 160 and inner back iron assembly 130 to piston assembly 114 during operation of linear compressor 100.

Piston assembly 114 includes a piston cylinder 180. Piston cylinder 180 includes a cylindrical segment 182 and a head plate 184. Head plate 184 is positioned at an end of piston cylinder 180. In particular, cylindrical segment 182 extends between a first end portion 186 and a second end portion 188, e.g., along the axial direction. Head plate 184 is mounted to or formed on cylindrical segment 182 at second end portion 188 of cylindrical segment 182.

Head plate 184 defines passage 118 of piston assembly 114. Passage 118 extends, e.g., along the axial direction A, through head plate 184. In particular, passage 118 extends from second end portion 188 of cylindrical segment 182 towards first end portion 186 of cylindrical segment 182 through head plate 184.

Piston assembly 114 further includes a reed valve 190. Reed valve 190 is mounted to head plate 184, e.g., such that reed valve 190 is positioned over passage 118 of head plate 184. Reed valve 190 is selectively adjustable between an open position and a closed position. In the open position, reed valve 190 permits fluid flow (e.g., air or refrigerant) through passage 118 of head plate 184 into chamber 112 of cylinder assembly 111. Conversely, reed valve 190 hinders or obstructs fluid flow through passage 118 of head plate 184 into chamber 112 of cylinder assembly 111 when reed valve 190 is in the closed position. Reed valve 190 actuates between the open and closed position depending upon a stroke direction of piston assembly 114 within chamber 112 of cylinder assembly 111. In particular, reed valve 190 actuates to the closed position as piston assembly 114 shifts from the bottom dead center position towards the top dead center position (e.g., on the compression stroke of piston assembly 114), and reed valve 190 actuates to the open position as piston assembly 114 shifts from the top dead center position towards the bottom dead center position (e.g., on the expansion stroke of piston assembly 114).

Reed valve 190 may be mounted to piston assembly 114 using any suitable method or mechanism. For example, a fastener 194 may be used to secure or mount reed valve 190 to piston assembly 114. In particular, fastener 194 may extend through reed valve 190 into head plate 184 in order to mount reed valve 190 to head plate 184. In alternative exemplary embodiments, reed valve 190 may be welded, adhered, etc. to piston assembly 114.

FIG. 12 provides a rear perspective view of piston assembly 114. As may be seen in FIG. 12, piston assembly 114 includes a post 195, e.g., mounted to head plate 184 and extending into cylindrical segment 182 along the axial direction A from head plate 184. Compliant coupling 170 may be mounted to piston assembly 114 at post 195. In particular, compliant coupling 170 may extend through cylindrical segment 182 and be mounted to head plate 184, e.g., at post 195. As an example, second end portion 174 of compliant coupling 170 may be threaded to post 195 or any other suitable portion of head plate 184. In such a manner, compliant coupling 170 may extend between inner back iron assembly 130 and piston assembly 114.

FIG. 13 provides a top, plan view of certain components of piston assembly 114. As may be seen in FIG. 13, a valve seat 196 is positioned on head plate 184 at passage 118. Valve seat 196 extends about passage 118, e.g., along the circumferential direction C and/or the radial direction R. Thus, passage 118 is surrounded or encircled by valve seat 196 at head plate 184. Valve seat 196 also extends away from head plate 184, e.g., along the axial direction A. Thus, a distal end of valve seat 196 is raised above head plate 184. Reed valve 190 is positioned on and contacts valve seat 196 above passage 118, e.g., when reed valve 190 is in the closed position. By having reed valve 190 rest on valve seat 196 in the closed position, a force required to open reed valve 190 can be reduced, e.g., by reducing an area that reed valve 190 contacts in the closed position. In addition, by having reed valve 190 rest on valve seat 196, a sealing force of reed valve 190 around passage 118 can be increased and/or leakages around reed valve 190 can be reduced or minimized.

Piston assembly 114 also includes a valve support 197. Valve support 197 is positioned at an outer edge 185 of head plate 184. Valve support 197 extends, e.g., along the circumferential direction C, along outer edge 185 of head plate 184. Valve support 197 also extends away from head plate 184, e.g., along the axial direction A. Thus, a distal end of valve support 197 is raised above head plate 184.

Valve seat 196 and valve support 197 defining a channel 198 therebetween. In particular, valve seat 196 and valve support 197 may be positioned on head plate 184 such that valve seat 196 and valve support 197 are spaced apart and do not contact each other. Thus, channel 198 may separate valve seat 196 and valve support 197 on head plate 184. Channel 198 may also assist with reducing an area contacted by reed valve 190 when reed valve 190 is in the closed position.

Turning back to FIG. 10, reed valve 190 defines an opening 199. Opening 199 of reed valve 190 extends through reed valve 190, e.g., along the axial direction A. Channel 198 may be contiguous with opening 199 of reed valve 190 when reed valve 190 is in the closed position. In addition, at least a portion of an outer edge 193 of reed valve 190 may be positioned, e.g., directly, over channel 198 when reed valve 190 is in the closed position.

As may be seen in FIG. 11, valve seat 196 extends away from head plate 184 by a height HV, e.g., along the axial direction A. The height HV of valve seat 196 may be any suitable height. For example, the height HV of valve seat 196 may be less than about five millimeters, less than about three millimeters or less than about one millimeter. Valve support 197 also extends away from head plate 184 by a height HS, e.g., along the axial direction A. The height HS of valve support 197 may be any suitable height. For example, the height HS of valve support 197 may be less than about five millimeters, less than about three millimeters or less than about one millimeter. In certain exemplary embodiments, the height HV of valve seat 196 is about equal to the height HS of valve support 197.

Passage 118 may have any suitable shape or cross-section. For example, passage 118 may define a substantially reniform cross-section, e.g., in a plane that is perpendicular to the axial direction A or in a plane that is parallel to an outer surface of head plate 184. The reniform cross-section of passage 118 may assist within increasing or maximizing a flow area or hydraulic diameter of passage 118 and reduce or minimize flow losses within passage 118.

Passage 118 may extend between a first end portion 191 and a second end portion 192, e.g., along the circumferential direction C. Thus, first and second end portions 191 and 192 of passage 118 are spaced apart from each other, e.g., along the circumferential direction C. In certain exemplary embodiments, passage 118 may extend along the circumferential direction C at least sixty degrees between first and second end portions 191 and 192 of passage 118. In alternative exemplary embodiments, passage 118 may extend along the circumferential direction C at least ninety degrees between first and second end portions 191 and 192 of passage 118.

It should be understood that piston assembly 114 may be used in any suitable linear compressor. Thus, while described in the context of linear compressor 100, piston assembly 114 may be used in any suitable linear compressor. In particular, piston assembly 114 may be used in linear compressors with moving inner back irons or in linear compressors with stationary or fixed inner back irons. It should be understood that piston assembly 114 may be formed or constructed such that cylindrical segment 182, head plate 184, valve seat 196 and valve support 197 are integral and/or continuous with each other. Thus, as an example, cylindrical segment 182, head plate 184, valve seat 196 and valve support 197 may be machined from single piece of metal, such as steel.

FIG. 14 provides an exploded view of a piston assembly 200 according to another exemplary embodiment of the present subject matter. Piston assembly 200 may be used in any suitable linear compressor. For example, piston assembly 200 may be used in linear compressor 100 as piston assembly 114 (FIG. 4). Piston assembly 200 includes similar features and components as piston assembly 114 and may be constructed in a similar manner.

As may be seen in FIG. 14, a head plate 212 of piston assembly 200 defines a plurality of passages 210. Passages 210 extend through head plate 212, e.g., along the axial direction A. Passages 210 are disposed within a valve seat 214 of piston assembly 200 at head plate 212. A reed valve 216 of piston assembly 200 is positioned over passages 210 and on valve seat 214 when reed valve 216 is in the closed position.

Passages 210 may include any suitable number of passages 210. For example, passages 210 may include two, three, four, five or more passages. Passages 210 may also have any suitable shape. For example, passages 210 may define a circular cross-section, e.g., in a plane that is perpendicular to the axial direction A. Passages 210 are spaced apart from each other, e.g., along the circumferential direction C. Passages 210 may also be positioned equidistant from the second axis A2 along the radial direction R.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A linear compressor, comprising: a driving coil; an inner back iron assembly positioned in the driving coil, the inner back iron assembly having an outer surface; a magnet mounted to the inner back iron assembly at the outer surface of the inner back iron assembly such that the magnet faces the driving coil; a cylinder assembly defining a chamber; a piston slidably received within the chamber of the cylinder assembly, the piston comprising a cylindrical segment extending between a first end portion and a second end portion; a head plate mounted to the cylindrical segment at the second end portion of the cylindrical segment, the head plate defining a passage that extends from the second end portion of the cylindrical segment towards the first end portion of the cylindrical segment through the head plate; a reed valve mounted to the head plate and positioned over the passage of the head plate; and a valve seat positioned at and extending about the passage of the head plate, the valve seat also extending away from the head plate such that the reed valve is positioned on the valve seat above the passage of the head plate when the reed valve is in a closed position; and a coupling extending between the inner back iron assembly and the piston.
 2. The linear compressor of claim 1, wherein a magnetic field of the driving coil engages the magnet in order to move the inner back iron assembly in the driving coil and the piston within the chamber of the cylinder assembly during operation of the driving coil.
 3. The linear compressor of claim 1, wherein the coupling extends through the cylindrical segment of the piston and is mounted to the head plate of the piston.
 4. The linear compressor of claim 3, wherein the coupling is threaded to the head plate of the piston.
 5. The linear compressor of claim 1, wherein the passage defines a substantially reniform cross-section in a plane that is parallel to an outer surface of the head plate.
 6. The linear compressor of claim 1, wherein the piston comprises a fastener extending through the reed valve into the head plate in order to mount the reed valve to the head plate.
 7. The linear compressor of claim 1, further comprising a valve support positioned at and extending along an outer edge of the head plate, the valve support also extending away from the head plate, the valve seat and the valve support defining a channel therebetween.
 8. The linear compressor of claim 7, wherein the reed valve defines an opening that extends through the reed valve, the channel being contiguous with the opening of the reed valve when the reed valve is in the closed position.
 9. The linear compressor of claim 7, wherein the valve seat extends away from the head plate by a height, the valve support also extending away from the head plate by a height, the height of the valve seat being about equal to the height of the valve support.
 10. The linear compressor of claim 1, wherein the head plate defines at least one additional passage that extends from the second end portion of the cylindrical segment towards the first end portion of the cylindrical segment through the head plate, the reed valve positioned over the additional passage of the head plate, the valve seat extending about the additional passage of the head plate.
 11. A linear compressor defining a radial direction, a circumferential direction and an axial direction, the linear compressor comprising: a cylinder assembly defining a chamber; a piston received within the chamber of the cylinder assembly such that the piston is slidable along a first axis within the chamber of the cylinder assembly, the piston comprising a piston cylinder having a head plate, the head plate positioned at an end of the piston cylinder, the head plate defining a passage that extends along the axial direction through the head plate; a reed valve mounted to the head plate and positioned over the passage of the head plate; and a valve seat positioned at and extending about the passage of the head plate along the circumferential and radial directions, the valve seat also extending away from the head plate along the axial direction; and a driving coil operable to move the piston assembly along a second axis, the first and second axes being substantially parallel to the axial direction.
 12. The linear compressor of claim 11, further comprising a coupling, the coupling mounted to the head plate and extending from the head plate through the piston cylinder along the axial direction.
 13. The linear compressor of claim 12, wherein the coupling is threaded to the head plate of the piston cylinder.
 14. The linear compressor of claim 11, wherein the passage defines a substantially reniform cross-section in a plane that is perpendicular to the axial direction.
 15. The linear compressor of claim 11, wherein the piston comprises a fastener extending through the reed valve into the head plate in order to mount the reed valve to the head plate.
 16. The linear compressor of claim 11, further comprising a valve support positioned at and extending along an outer edge of the head plate, the valve support also extending away from the head plate along the axial direction, the valve seat and the valve support defining a channel therebetween.
 17. The linear compressor of claim 16, wherein the reed valve defines an opening that extends through the reed valve, the channel being contiguous with the opening of the reed valve when the reed valve is in a closed position.
 18. The linear compressor of claim 16, wherein the valve seat extends away from the head plate by a height along the axial direction, the valve support also extending away from the head plate by a height along the axial direction, the height of the valve seat being about equal to the height of the valve support.
 19. The linear compressor of claim 11, wherein the passage extends between a first end portion and a second end portion along the circumferential direction, the passage extending along the circumferential direction at least sixty degrees between the first and second end portions of the passage.
 20. The linear compressor of claim 19, wherein the passage extends along the circumferential direction at least ninety degrees between the first and second end portions of the passage. 